they should be easy enough to paint.

you'll have to lightly sand w/150 then 220, ( you want to remove as much of the gloss finish as possible) wipe clean w/mineral spirits, prime with a good oil base primer like Zinsser, or a Bin Shellac (otherwise those knots will bleed through) Fine sand again w/220 until the surface is nice and smooth, wipe clean and make sure no residue/dust is left there (use a vacuum)

then use two coats of a semi gloss wood trim paint like BM Advance, or SW ProClassic

it's not difficult but it is a lot of work. 13 is a lot to do.

If you aren't happy w/the windows and plan on replacing them, you'll have to get pre-primed white MDF casing. those are already to paint. (after filling in the nail holes)

I don't want to paint -- I really want stained trim. Although, are you suggesting painting the frames and then I could re-do the casings in a different stain?

those look like pine. if you want to stain you'll have to remove ALL of the previous finish on there. Look at all those nooks and crannies around that window. you'll be sanding for days to remove all of it.

and if you try going over that stain w/a darker gel stain, it won't look good. Pine is rather blotchy and doesn't take darker stains very well.

I'm actually talking about painting your casings. I'd start w/that first and see if it makes it look less orange.

if you want to tackle the interior portion of the window itself, you will have to remove all of that old finish. I suspect the top clear coat has yellowed w/time and that's why it's so orange looking. you ever refinished wood? it's a lot of work. that's why I mentioned just painting the whole shebang.

I'd prob leave the wood next to the glass as is.

No, I would need to hire this out -- I am not a DIY-er, and DH doesn't have the time for a project like this. Which is why I thought maybe just scrapping these casings and having new ones put up in a stain I like is an option. But then I'm back to the what to do about the frame issue.

I would check in the painting forum , there products than can tint but there would be limitations. There are good painters that specialize in this type of work, one that specializes in spraying cabinets may be a place to start. The knots are going to show but would be more hidden in a darker stain/dye.

if she wants stain, the old finish has to be removed. applying a new finish on top of an old finish will not yield good results. And dying wood, well that has to have raw wood w/no finish at all. I've done it. The aniline dye is water based. It actually absorbs into the wood, dyeing it. And that's where the labor comes into play. sanding or stripping off the old finish. There's no way around it. If you want a new stain color, the old stain/clear coat has to be removed. period. (unless you want a crap job. in that case, just fine sand and rub on a darker gel stain color. )

That's why I mentioned priming and painting. less labor costs

btw, most painters don't specialize in wood finishing. That's a whole other skill set. They may employ wood finishers, but most run-of-the-mill house painters aren't wood finishers.

This sounds like it's going to be expensive, unfortunately. I do have a painter I trust, I can ask him for recommendations for someone who specializes in wood refinishing. I do have a rec for a trim carpenter in my area, he might also be a good place to start for advice on exactly what to do -- at the least, what building new casings will cost. Ugh, I wish I had the skills for this sort of thing -- DH has the basic carpentry skills, he just doesn't want to do it. Sigh...